Traditional broadcast FM radio receivers use discrete analog intermediate frequency (IF) filters for selecting and filtering the desired signal, and analog demodulators that demodulate the FM signal in order to extract the audio signal. These receivers are typically analog and their performance is determined by the precision and variability of the analog components.
Advances in complementary metal-oxide-semiconductor (CMOS) fabrication and digital signal processing (DSP) technology have made channel filtering and frequency modulation (FM) demodulation possible in the digital domain. Some integrated FM receivers use digital filters for channel selection, digital FM demodulation and an analog-to-digital converter (ADC) for facilitating digitization of the down-converted IF signal within a single channel bandwidth. The FM channel for a single radio station can be 150 kilohertz (KHz) wide, determined by the maximum FM deviation of ±75 kHz. The ADC can have a 150 kHz pass band, centered at the IF frequency. The receiver front-end and the ADC provide some filtering but the majority of the channel filtering is done by the digital channel-select filter. The filtered single channel is then demodulated digitally.